"He is now, at this moment, in hospital," Blatter's spokesman Klaus Stoehlker told AFP by phone. "He is preparing to leave on Monday and will be back on the job on Tuesday."
Stoehlker added that 79-year-old Blatter had "regained his good humour" and has vowed to persist with "his fight against the (FIFA) ethics committee" which suspended him for 90 days over corruption allegations.
Blatter, long the most powerful man in football, suffered a medical incident last weekend and had been placed under medical observation from his home.
Stoehlker previously said the stress-related medical incident had been brought on by the pressure the embattled Swiss national has faced in recent weeks.
Blatter has been at the centre of the worst scandal to ever hit world football. Swiss prosecutors opened a criminal case against him in September, an announcement that led to his suspension from FIFA.
Before he was suspended, Blatter, who has been in charge of FIFA since 1998, had said he would step down on February 26, next year, when a FIFA congress elects a new president.